Conventionally, the underbody structure of a vehicle forming the floor of the vehicle is arranged to protect the vehicle occupants in case of an impact, in particular a side impact or a front impact by limiting intrusions of any kind in the vehicle passenger compartment.
To this end, the underbody structure comprises reinforcement elements arranged transversally between structural longitudinal elements, such as underfloor longitudinal beams. This assembly is arranged to prevent the deformation of the vehicle compartment and to maintain the integrity of the floor panel in case of an impact, thereby protecting the occupants of the vehicle.
While this arrangement can be efficient in case of a side impact, i.e. an impact occurring in the transversal direction, and in case of a full front impact, i.e. an impact occurring in the longitudinal direction at the front or rear of the vehicle, a risk remains in the case of a front impact offset relative to the center of the vehicle, called “small overlap crash”, regulated by the United States of America's Insurance Institute for Highway Safety. During such a small overlap crash, the impact occurs in the longitudinal direction at the front of the vehicle outboard of the longitudinal structural elements, i.e. on 25% or less frontal overlap of the vehicle. In this case, the regular impact absorbing elements provided at the front of the vehicle do not fully fulfill their function since the impact does not occur in front of the longitudinal beams of the vehicle.
In this case, as shown in FIGS. 5 and 6 representing respectively a view from below and a view from above of part of a conventional vehicle underbody structure after a small overlap crash, the wheel of the vehicle located on the same side as the impact barrier, tends to rotate towards the interior of the vehicle and to deform the floor panel at a location where the feet of an occupant of the vehicle are usually placed. Consequently, such an impact can cause significant damage to the occupant's legs.